9. 6: Option - Shipwrecks, Corrosion and Conservation
9. 6.1: The chemical composition of the ocean implies its potential role as an electrolyte

Identify the origins of the minerals in oceans as:

• leaching by rainwater from terrestrial environments
• hydrothermal vents in mid-ocean ridges

Identify - recognise and name

There are 2 major sources of the salts in seawater:

1. Leaching by rain and ground water.
2. Dissolution of salts by water passing through hydrothermal vents.

LEACHING BY RAIN AND GROUND WATER

• The main ions that are dissolved as rainwater percolates through the soil and makes its way into creeks and rivers are Na, Ca, Mg, Cl and SO4.
• Water that seeps down into underground aquifers dissolves greater quantities of these ions and under certain conditions (slightly lower pH than normal) picks up significant amounts of Hydrogen Carbonate (by dissolving carbonate)
• Small amounts of nitrate and phosphate are also dissolved: these result from decay of plant...